Thermoelectrically cooling electronic devices

ABSTRACT

A heat sink may be clamped to a thermoelectric cooler and vapor chamber using a U-shaped retention band. The band may attach underneath the vapor chamber, extending around the thermoelectric cooler, and over a heat sink. The heat sink may include a plate to distribute the force of the band across the heat sink. Bolts may be utilized to transfer the force from the free ends of the U-shaped retention band to a vapor chamber support frame. Thus, in some embodiments of the present invention, a thermoelectric cooler may be clamped to a heat sink without wasting heat transfer area through the use of bolts, without unnecessary bending, and without requiring a relatively thick base on the heat sink.

BACKGROUND

This invention relates generally to techniques for cooling integratedcircuits.

Integrated circuits may develop heat in the course of operation. Thisheat may result in device failure. It may also adversely affect theperformance of the overall system, including the electronic device.Therefore, it is desirable to cool the electronic device and systemsusing the electronic device.

To this end, a variety of cooling techniques have been used for coolingelectronic devices. A thermoelectric cooler generates cool temperaturesproximate to an electric component. The thermoelectric cooler mayoperate in conjunction with a heat sink. In such cases, there is a needfor techniques for joining the heat sink, the thermoelectric cooler, andthe component to be cooled.

Because the heat sink may have relatively little rigidity, simplybolting the parts together may result in bending moments at the edges,which may result in bowing of the heat sink. Such bowing of the heatsink may result in insufficient thermal interface between the heat sinkand the thermoelectric cooler. That insufficient thermal interfaceresults in less effective cooling. Using a thicker heat sink base is onesolution. However, the resistance to thermal dissipation is a functionof the thickness of the heat sink base.

Thus, there is a need for better ways to form thermoelectric coolingdevices for electronic circuits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of one embodiment of the present invention;

FIG. 2 is an enlarged, cross-sectional view of the vapor chamber shownin FIG. 1 in accordance with one embodiment of the present invention;

FIG. 3 is a perspective view of the retention band shown in FIG. 1 inaccordance with one embodiment of the present invention;

FIG. 4 is a perspective view of the assembled cooling device inaccordance with one embodiment of the present invention, viewed at anangle from above;

FIG. 5 is a perspective view corresponding to FIG. 4, viewed from below;and

FIG. 6 is a side view of a system using the cooling structure shown inFIGS. 1 through 5 in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION

Referring to FIG. 1, a finned heat sink 12 may include a large number offins 13 coupled by a flexible base 15. The fins 13 may be formed asparallel plates secured to the base 15 in one embodiment of the presentinvention. Below the heat sink 12 is a thermoelectric cooler 14.Underneath the thermoelectric cooler is a vapor chamber 16 for thethermoelectric cooler 14. A vapor chamber support frame 18 underlies thevapor chamber 16.

Referring to FIG. 2, the vapor chamber 16 may include a top wall 22, abottom wall 28, and a sidewall 24. Standoffs 26 may allow room for aliquid/vapor phase 30 between the walls 24 and 28.

Referring to FIG. 3, in accordance with one embodiment of the presentinvention, a U-shaped clamp or retention band 11 may include a bowed orpre-bent, leaf spring connecting portion 32 and downwardly extendingtransverse arms 34. The free end of each arm 34 may include a boltretainer 36 and an upstanding bolt 38 in one embodiment of the presentinvention. The band 11 may be resilient in one embodiment.

The components of FIG. 1 may be secured together using the retentionband 11. In particular, as shown in FIGS. 4 and 5, the band 11 maytraverse the heat sink 12. Damage to the heat sink 12 may be avoided byproviding the fin array plate 20, which further stabilizes the heat sink12. The entire structure is clamped together by the juxtaposition of thebolts 38 against the bottom of the vapor chamber support frame 18. Insome embodiments, the amount of force applied may be adjusted byadjusting the amount by which the bolts extend through the retentionunits 36. In addition, the force applied is controlled by thepre-bending of the connecting portion 32.

Referring to FIG. 6, the cooling structure 10 may be mounted over apackage 44 having a shape adapted to receive the bolts 38 and boltretainers 36. A substrate 46, socket 48, and a printed circuit board 50may be provided to connect the cooling device 10 to an appropriateelectronic system. A fan 42 may force air through the heat sink 12, inone embodiment of the present invention, in a direction parallel to thelength of the heat sink fins 13. Heat given off by the thermoelectriccooler 14 is removed to the atmosphere by the flow of air over the heatsink 12.

In some embodiments, the components may be made up by providing athermal interface material, such as grease, between the various layers.A minimum pressure between the thermoelectric cooler surfaces, the heatsink, and the vapor chamber may provide the desired thermal resistanceat those interfaces. In some cases, it is advantageous to provide theair flow from the side of the heat sink instead of the top. Multipleretention bands may be utilized to ensure that the load is spread evenlyacross the entire fin array in some embodiments. If it is desired tomaintain the open area at the top of the fin array, several smallerbands, spaced from one another, may be employed. In other cases, asingle, solid, retention band may be utilized.

In some embodiments, a thermoelectric cooler stackup may be utilizedwithout providing unnecessary bending. These bending problems may breakthe good thermal interface between the components. It may also bedesirable to provide the stackup without unduly thickening the base ofthe heat sink. Because of the band 11, the compressive load may bedistributed over the entire fin array in some embodiments. In addition,using threaded connectors may interfere with the operation of thethermoelectric cooler and may result in loss of heat transfer area.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

1. A method comprising: clamping a heat sink to a thermoelectric coolerover a vapor chamber using a clamp that extends at least partiallyaround said thermoelectric cooler and vapor chamber over the top of saidheat sink.
 2. The method of claim 1 including clamping a heat sink usinga U-shaped member which clamps to a plate underneath the heat sink andextends around and over the heat sink from side to side.
 3. The methodof claim 2 including providing adjustable threaded members on the freeends of said U-shaped heat sink.
 4. The method of claim 1 includingproviding a reinforcement over the top of the heat sink to underlie theclamp.
 5. The method of claim 1 including providing a stack of said heatsink, a heat spreader, a thermoelectric cooler, and a vapor chamber. 6.The method of claim 5 including providing a support frame underneathsaid vapor chamber.
 7. The method of claim 6 including clamping aU-shaped clamp on the underside of said support frame.
 8. The method ofclaim 7 including causing said clamp to extend from the underside ofsaid support frame, around the side of said heat sink, over said heatsink, down the opposite side of said heat sink, and under said supportframe on the opposite side.
 9. The method of claim 8 including providingan adjustment means at the interface between said clamp and said supportframe.
 10. The method of claim 9 including providing a clamp with aconnecting portion and a pair of transversely extending arms, saidconnecting portion being bowed and said arm being resilient.
 11. Themethod of claim 10 including arranging said connecting portion to pressagainst the upper surface of said heat sink when said transverselyextending arms are clamped underneath said heat sink to provide a springbiased compression between said clamp and said heat sink.
 12. The methodof claim 1 including securing said clamp on fins extending from saidheat sink.
 13. A clamp comprising: a bowed leaf spring connectingportion; and a pair of transversely extending arms extending fromopposed ends of said portion, said arms to wrap around a vapor chamber,a thermoelectric cooler, and a heat sink to secure said heat sink tosaid thermoelectric cooler and vapor chamber.
 14. The clamp of claim 13including an adjustment element on the free ends of said arms.
 15. Theclamp of claim 14 wherein said adjustment element includes a threadedmember.
 16. The clamp of claim 13 wherein said portion bows toward saidarms.
 17. A cooling assembly comprising: a heat sink having fins; avapor chamber; a thermoelectric cooler; and a U-shaped clamp extendingover said fins and under said vapor chamber and thermoelectric cooler toclamp said vapor chamber and cooler to said heat sink.
 18. The assemblyof claim 17 including a strip extending over said fins, and under saidU-shaped clamp.
 19. The assembly of claim 17 wherein said clamp includesa bowed leaf spring connecting portion and a pair of transverselyextending arms extending from opposed ends of said portion.
 20. Theassembly of claim 19 including threaded members on the free ends of saidarms.
 21. The assembly of claim 17 including a vapor chamber coupled tosaid cooler.
 22. The assembly of claim 21 including a vapor chambersupport frame coupled to said vapor chamber.
 23. The assembly of claim17 wherein said U-shaped clamp includes a bowed portion extending oversaid fins, said bowed portion being resilient.
 24. The assembly of claim17 including a vapor chamber and a vapor chamber frame, said U-shapedclamp extending over said fins, said cooler, said vapor chamber, athermoelectric cooler, and abutting against said vapor chamber supportframe.